1. Field of the Invention
The present invention relates generally to a support structure for torque transmission elements of an automotive transmission including planetary gear arrangments shift units, etc.
2. Description of the Related Art
An automotive transmission structure is known comprising a shift unit having a planetary gear arrangement situated around an shaft receiving input torque from a driving source, such as a vehicle engine, or the like. According to this structure a first output gear and a first shaft have the same rotational axis. In such a structure for a shift unit of an automotive transmission, a first torque input side and a first output gear are disposed on opposite sides of a first shaft. The reverse arrangement is also possible.
One example of such a conventional structure is disclosed in Japanese Utility Model Application first publication No. 2-48649. This application discloses a transmission gear support arrangement such as shown in FIG. 4. Referring to FIG. 4, a first input shaft 01 receives input torque from a torque converter (not shown) at one end thereof and a planetary gear arrangement (shift unit) 02 is disposed at the opposite end of the shaft 01. An output projection 03 connected to a carrier of the shift unit 02 is disposed on an outer circumferential surface of the first input shaft 01 to engage a first output (counterdrive) gear 04 which engages a first gear 06 having a rotational axis on a second shaft 05 parallel to the first input shaft 01. The first output gear is mounted via bearings 07, 09 for free rotation thereof. The first bearing 07 is mounted at an inner side of a wall portion 08 of the transmission casing disposed around the first input shaft 01, output projection 03 and the first output gear 04 etc., and the second bearing 09 is supported by a wall portion 011 projected from a pump body 010.
According to the above disclosed structure, the first output gear 04 is disposed close to the torque input end of the first input shaft 01, this arrangement is favorable for a vehicle with a laterally mounted engine since the distance of the output gear and the differential is close and the length of the second shaft 05 may be made shorter. Thus high efficiency is obtained.
However, according to such arrangement, mounting of the first output gear 04 requires a plurality of bearing portions 07, 09 to be installed which must have the same rotational axis while supported by different internal wall structures 08, 011 associated with the transmission casing and the pump body 010. Thus, complexity of assembly and a number of parts necessary is increased. Also a required accuracy of assembly is raised and costs are increased correspondingly.
Thus, it has been required to provide a simplified structure for a transmission gear support in which compactness and efficiency are maintained at lower cost with less complexity and fewer parts and which may be installed relatively easily.